This invention relates to a prosthetic medical device and methods, and more particularly to methods of connecting electrical conducting wires to a miniature implantable device to minimize risk to the living tissue during and after surgery.
Neurological disorders are often caused by neural impulses failing to reach their natural destination in otherwise functional body systems. Local nerves and muscles may function, but, for various reasons, such as injury, stroke, or other cause, the stimulating nerve signals do not reach their natural destination. For example, paraplegic and quadriplegic animals have intact nerves connected to functioning muscles and only lack the brain-to-nerve link. Electrically stimulating the nerve or muscle can provide a useful muscle contraction.
Further, implanted devices may be sensors as well as stimulators. In either case, difficulties arise both in providing suitable, operable stimulators or sensors which are small in size and in passing sufficient energy and control information to or from the device, with or without direct connection, to satisfactorily operate them. Miniature monitoring and/or stimulating devices for implantation in a living body are disclosed by Schulman, et al. (U.S. Pat. No. 6,164,284), Schulman, et al. (U.S. Pat. No. 6,185,452), and Schulman, et al. (U.S. Pat. No. 6,208,894).
It must be assured that the electrical current flow does not damage the intermediate body cells or cause undesired stimulation. Anodic or cathodic deterioration of the stimulating electrodes must not occur.
In addition, at least one small stimulator or sensor disposed at various locations within the body may send or receive signals via electrical wires. The implanted unit must be sealed to protect the internal components from the body""s aggressive environment. If wires are attached to the stimulator, then these wires and the area of attachment must be electrically insulated to prevent undesired electric signals from passing to surrounding tissue.
Miniature stimulators offer the benefit of being locatable at a site within the body where a larger stimulator cannot be placed because of its size. The miniature stimulator may be placed into the body by injection. The miniature stimulator offers other improvements over larger stimulators in that they may be placed in the body with little or no negative cosmetic effect. There may be locations where these miniature devices do not fit for which it is desired to send or receive signals. Such locations include, but are not limited to, the tip of a finger for detection of a stimulating signal or near an eyelid for stimulating blinking. In such locations, the stimulator and its associated electronics are preferably located at a distance removed from the sensing or stimulating site within the body; thus creating the need to carry electrical signals from the detection or stimulation site to the remote miniature stimulator, where the signal wire must be securely fastened to the stimulator.
Further, the miniature stimulator may contain a power supply that requires periodic charging or require replacement, such as a battery. When this is the case, the actual stimulation or detection site may be located remotely from the stimulator and may be located within the body, but removed a significant distance from the skin surface. By having the ability to locate the miniature stimulator near the skin while the stimulation site is at some distance removed from the skin, the miniature stimulator and its associated electronics can be more effectively replaced by a surgical technique or more efficiently recharged through the skin by any of several known techniques, including the use of alternating magnetic fields. If the electronics package is replaced surgically, then it is highly desirable to have the capability to reconnect the lead wires to the miniature stimulator via an easy, rapid and reliable method, as disclosed herein.
The instant invention relates to apparatus and methods for connecting an electrically conductive wire to a miniature, implantable stimulator. The stimulator case is comprised of electrically insulating materials such as plastic or ceramic. The plastic may be epoxy, polycarbonate, or plexiglass. The ceramic may be alumina, glass, titania, zirconia, stabilized-zirconia, partially-stabilized zirconia, tetragonal zirconia, magnesia-stabilized zirconia, ceria-stabilized zirconia, yttria-stabilized zirconia, or calcia-stabilized zirconia. There is at least one electrically conductive electrode for conducting electrical signals. The materials comprising such electrically conductive parts are selected to reduce or eliminate damage due to corrosion from the tissue environment surrounding the miniature stimulator, and also to avoid damage to the tissue, for example, not being toxic or having sharp corners that can damage the tissue.
The electrical connection between the electrically conductive case parts and the electrically conductive wires is accomplished by several methods, including the use of crimping, welding, threading, or interlocking by bayonet means, snap-on means, screwing-on means, or pin means. The wire may also be secured to the electrode in a variety of novel ways, including, compression fits between the cap and electrode that secure the wire by compression fit.
The electrode may be either a male pin or a female receptor configuration. Apparatuses for insulating the electrode from the body and for making attachment of a wire to the electrode are disclosed. Some of these approaches to making safe and secure electrical connections between and electrode and wire include bayonet mounting of the cap to the electrode, crush lips to secure the wire between the cap and the electrode, and spade clips to allow quick and secure attachment of the wire to the electrode.
In any of these approaches to making a secure and safe connection of wire to connector attachment, the entire connection area and wire must be electrically insulated from the body. Placing a flexible insulating boot over the entire stimulation wire connection accomplishes this. The insulating boot is preferably held in place with at least one of several methods, including ties, C-clips, silicone adhesive or a tight fit with or without a securement ridge.
Each connection mechanism allows for the use of a wire with at least one separate element, each of which may carry an independent electrical signal. Further multi-connector slip cap or feedthrough apparatuses are disclosed which allow multiple independent electrical connections to be made in a single maneuver during surgery.
This invention offers a variety of configurations to the surgeon, both pre-surgery and during surgery. Changes may be made to the configuration to accommodate necessary modifications during surgery and during secondary surgeries at a later time. Corrosion is prevented or significantly reduced by the proper selection of materials and the use of an electrically insulating boot in combination with secure attachment methods.
It is an object of the invention to provide an implantable miniature stimulator having at least one electrode.
It is an object of the invention to provide a method of connecting at least one wire to a miniature stimulator in a body.
It is an object of the invention to increase the ease and safety of a surgeon making electrical connections for in vivo application of a miniature implantable stimulator.
It is an object of the invention to connect the electrode of a miniature implantable stimulator in a secure, safe and rapid fashion to electrical wires.
It is an object of the invention to electrically insulate the electrode of an implantable miniature stimulator that is connected to an electrical wire from the body environment in which it is implanted.